
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* #one {
      color: red;
    }

    .son {
      color: blue;
    }

    p {
      color: green;
    } */

    /* (行内, id, 类, 标签) */

    /* (0, 0, 0, 1) */
    div .son {
      color: orange;
    }

    /* (0, 0, 2, 0) */
    .father .son {
      color: skyblue;
    }

    /* 0, 0, 1, 1 */
    .father p {
      color: purple;
    }

    /* 0, 0, 0, 2 */
    div p {
      color: pink;
    }

  </style>
</head>
<body>
<div class="father">
  <p class="son" id="one">我是一个标签</p>
</div>
</body>
</html>